Photographic process



June 15, 1943. c. 1.. A. WYND EIAL L PHOTOGRAPHIC PROCESS Original FiledSept. 23, 1941 FgJ PHOTOGRA PH/ C LA YER SCREEN/N6 LAYER. LAYER OFLUM/NESCENT MATERIAL.

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C/arenceLAMj/nd Gerou/a TLane INVENTORS y Wm ATTORNEY Patented June 15,1943 UNITED STATES PATENT OFFKIE PHOTOGRAPHIC PROCESS New JerseyOriginal application September 23, 1941, Serial No. 411,968. Divided andthis application May 1, 1942, Serial No. 441,280

Claims.

This invention relates to the reproduction of engineering drawings andthe like, and particularly to the photographic reproduction of suchdrawings when using opaque materials throughout. This is a division ofour application Serial No. 411,968 filed September 23, 1941.

In the making of metal templates or patterns for industrial productionit has been customary to prepare the original drawings which were thenredrawn to scale on the work material by hand. This time-consuming andlaborious method of preparing the templates or patterns (usually metal)was subject to errors and recently has been replaced to some extent byphotographic copying and reproduction. One such process, disclosed inPatent No. 2,303,942 granted December 1, 1942, to the present inventors,makes use of a drawing delineated by fluorescent material and contactprinted on a photographic layer carried by that work material. Theresulting print of the drawing is, of course, a mirror image of theoriginal and for convenience will-be referred to herein as a negative.When the print is not a mirror image but is a duplicate it will bereferred to as a positive without regard to whether it is black on whiteor white on black.

For obvious reasons it is highly desirable to be able to produce on themetal work sheets several positive duplicates of the original drawingsor selected portions of it. This is made possible by the presentinvention which provides a complete process of making photographicreproductions via the negative, positive method and using opaquematerial throughout.

According to the preferred embodiment of the invention, the originaldrawing is made on a layer of fluorescent material carried by an X-raypermeable, rigid support, such as aluminum or plywood. This drawing ismade with a lacquer or pencil which is opaque to the luminescent lightfrom the layer. It may also be made by scriving or engraving in afluorescent layer, by drawing with a fluorescent lacquer or pencil upona non-fluorescent layer, or by any other means forming an image whichwhen activated by light, X-rays or other radiant energy is rendereddifferentially luminous. The luminescent material may be of a suitablephosphor such as calcium tungstate as proposed in our Patent 2,303,942or barium fluorochloride as described in the patent of Herbert J. Dietz,No. 2,303,917, granted December 1, 1942. The lightfrom this is in theviolet and ultraviolet region to which ordinary photographic emulsionsare highly sensitive. This drawing is placed in contact with aphotographic layer carried by an X-ray permeable support and exposed byactivating the fluorescent layer with X-rays which may be directedthrough either support. Now, in order that the resulting negative printmaybe similarly printed to provide a positive, a fluorescent layer isprovided under its photographic layer and a removable screening layer ispreferably provided between the two so that, when the photographic layeris exposed and developed and the screening layer removed, there resultsa negative equivalent of the original drawing. This negative may beprinted on a photographic layer by activating the fluorescent layer ofthe negative with X-rays in the same general way the negative was madefrom the original.

In addition to making a negative on a fluorescent layer, the originalmay also be employed to print negative template material. Thus, byhaving both a positive and a negative from which contact prints can bemade, it is simplicity itself to provide the exactly symmetricaltemplates so often required in the type of manufacturing for which suchtemplates are best adapted. For example, it the original drawingrepresents the right front door of an automobile, the negativefluorescent print will represent the left front door, and the templatesfor the right and left doors will be made by contact printing thefluorescent negative and the fluorescent original, respectively.

Instead of using fluorescent material any suitable luminescent materialmay be employed. This material may then be activated with the properradiation, such as ultra-violet light, cathode rays, X-rays, etc. Itwill be understood that when the activating radiation is not transmittedby the support, the exposure will be made by phosphorescent light. Also,the sensitive photographic layer carried by the element of my inventionmay be exposed as desired, whether by means of a luminescent drawing orby means of ordinary light when the drawing to be printed thereon iscarried by a transparent support, such as plate glass.

The luminescent drawing may be exposed to X-rays or other activatingrays while separated from the sensitive plate and at once moved intocontact with it, the exposure of the sensitive plate being then causedentirely by the after-glow or phosphorescence.

In the drawing:

Fig. 1 is a cross-sectional view of a light-sensitive element made inaccordance with the invention;

Fig. 2 is a sectional view showing this element being given anepipolized printing exposure; and

Fig. 3 is a sectional view showing a photographic record -made inaccordance with the invention.

In Fig. 1 an opaque support I is provided with a plurality of layers,the first of which is a layer H of luminescent material, the next layerI2 is a screening layer adapted to shield the outer light-sensitivelayer II from the luminescence of the layer II. The luminescent materialof layer Il may be calcium tungstate incorporated in a water-resistantmedium, such as a cellulose ester solution. The screening layer IIshould be capable of being made transparent and preferably is one whichmay be decolorized either by action of a photographic processing bath ora separate bleaching bath. A satisfactory screening layer 12 may be madeof manganese dioxide or a non-wandering dye suspended in awaterpermeable medium, such as gelatin, far hydrolyzed cellulose esters,or resinous materials of like properties, in order that this layer I!may be decolorized by the aqueous processing or bleaching baths.

A photographic layer I3 is preferably of the process type and may beeither a gelatino silver halide emulsion or one prepared from suitablyprepared cellulose esters or resins. These may be adapted to be spreador brushed onto the base material and, of course, suitable subbinglayers of known types should be used to secure satisfactory adhesionbetween the various layers.

In view of the fact that, in the industrial art for which the presentinvention is particularly suitable, the sheets upon which the drawingsare made and reproduced range in size up to six feet wide and twentyfeet long, it is not a simple matter to appl the photographic layer l3,and for this reason we prefer to make use of the transfer film describedand claimed in an application, Serial No. 397,093, filed June '1, 1941,by G. T. Lane, one of the present inventors by which an unexposedsensitized layer is applied to the large'metal plate.

Although at the present time it is preferred to practice the inventionas above described, the invention has been practiced in other ways toobtain the same desirable results. For instance, the fluorescent layerupon which the drawing is made can be prepared so that it transmits arelatively small proportion of the X-rays employed to activate it. Thus,the screening layer of the photographic element may be omitted becauseits underlying fluorescent layer will not be sufliciently activated toproduce an intolerable fogging exposure. A similar result can beobtained by carefully choosing the X-ray exposure, both as to hardnessand time, best adapted for the fluorescent material employed and thesensitivity of the emulsion to be exposed.

There may also be used a sensitive material which is insensitive to thelight given off by the luminescent layer carried on the same support.

When the process of the present invention is practiced usingphosphorescent light for copying the original drawing, a screening layerbetween the sensitive layer l3 and the underlying luminescent layer IIis unnecessary, and the print may be made on a photographic layerdirectly overlyin the luminescent layer.

It will be evident from the above description that the present inventionmakes it possible and practical to make a photographic copy on a rigidopaque support, which copy may be printed onto another photographiclayer carried by an opaque support. It will be understood that theusefulness of the element of the present invention is not limited toprocesss in which it is printed from a drawing or printed onto aphotographic layer carricd by an opaque support.

What we claim and desire to secure by Letters Patent of the UnitedStates is:

l. The method of preparing a negative in terms of luminescent andnon-luminescent areas of an original drawing defined by luminescent andnonluminescent areas which comprises exciting the luminescent areas ofthe original to make them luminesce, exposing to the resultingluminescing image a light-sensitive emulsion overlyin a layer ofluminescent material carried by an opaque support and developing theexposed layer.

2. The process of making photographic reproductions which comprisesmaking on a first element an image having luminescent areas, exposingsaid image to radiant energy exciting said areas, holding said elementwhile thus excited in contact with a second element having aphotographicall sensitive layer, and also a luminescent layer, whereby alatent image from the rays emitted by the first element is formed insaid photographic layer, developing a light obstructing image in saidphotographic layer, submitting said second element to radiant energycapable of exciting said luminescent layer carried thereby and holdingsaid second element while thus excited in contact with a third elementcarrying a photographic layer whereby a latent image is formed in saidphotographic layer on the third element.

3. The process of making photographic reproductions which comprisesmaking on a first element an image comprising areas which becomeluminescent when excited by X-rays and nonluminescent areas, holdingsaid element in contact with a second element carrying a photographiclayer and also a layer which when excited by X-rays becomes luminescent,exposing said elements while in contact to X-rays whereby saidluminescent areas are activated and emit rays which impress saidphotographic layer, developing a photographic image in said photographiclayer, holding said second element in contact with a third elementcarrying a photographic layer and exposing said element while in contactto X-rays whereby the luminescent layer is excited and emits rays whichimpress a latent image in the photographic layer carried by the thirdelement except where such rays are intercepted by the image in thesecond element.

4. The process of making photographic repro ductions which comprisesmaking on a first element an image comprising areas which are renderedluminescent when excited by X-rays, holding said element in contact witha second element carrying a photographically sensitive layer and a layerwhich is rendered luminescent when e:- cited by X-rays, the photographiclayer being substantially unaffected by the luminescent light from thesecond element, exposing said elements while in contact to X-rayswhereby the luminescent areas on the first element are excited andimpress an image in the photographic layer, holding said second elementin contact with a third element carrying a photographic layer andexposing said elements while in contact to X- rays, whereby theluminescent layer is excited and impresses an image in said photographiclayer carried on the third element except where the rays are interceptedby said image.

5. The process of making photographic reproductions which comprisesmaking on a first element an image comprising areas which becomeluminescent layer opaque to rays emitted by said element in contact witha second element carrying a photographic layer, a layer which becomesluminescent when excited by X-rays and a. screening layer between saidphotographic layer and said luminscent layer opaque to rays emitted bysaid luminescent layer, and exposing said elements while in contact toX-rays whereby the luminescent areas on the first element are excitedand impress said photographic layer, developing an image in saidphotographic layer and rendering said screening layer transmissive ofthe luminescent rays, holding said second element in contact with athird element carrying a photographic layer and exposing said elementswhile in contact to X-rays whereby the luminescent layer is excited andemits rays which impress a latent image in the photographic layer on thethird element except when the rays are intercepted by the 1 developedimage.

CLARENCE L. A. WYND. GEROULD '1'. LANE.

CERTIFICATE OF CORRECTION. Patent No. 2, 22,082. June 1 19%.

CLARENCE L. A. WYND, ET AL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as followsi Page 5, ircolumnjcline 5, claim 5, strike out the words "layer opaque to raysemitted by and insert instead --when excited by x-rays holding"; andthat the said Letters Patent should be read with this correction thereinthat the same may conform to the record of the case in the PatentOffice.

Signed and sealed this 29th day of February, A. D. 19bit.

Leslie Frazer 8 Acting Commissioner of Patents.

